Rubber heel



J. w. AYMAR, JR

RUBBER HEEL Original Filed Sept. 27, 1921 Waff-1 ATTORNZ Patented Dec. 15, 1925.

UNITED STATES PATENT i OFFICE.

JOHN W. AYMAR, JR., OF NEW YORK, N; Y.

RUBBER HEEL.

Application led September 27, 1921, Serial No. 503,604. Renewed February 28, 1923.

fl 'o all whom t may concern vBe it known that I, JOHN W. AYMAR, J r., a citi/:en of the United States, and resident of the borough of Manhattan, city, county,

and .citate of New York, have invented certain new and useful Improvements in Rubber Heels, of which the following is a specification.

lhis invention relates to resilient heel lifts and in its generic aspect has for its object to provide an improved lift for shoe heels of rubber or other resilient material which is of such construction that certain material disadvantages existing in heel lifts of the constructions now in general use are entirely obviated.

It has heretofore been proposed to provide what is known as a concave-convex rubber heel or lift in which the attaching and tread faces are double curve surfaces. In the ap plicaton of such heel lifts to the leather heel of the shoe whenthe lift is flattened against the shoe heel it is impossible to bring all parts of the concave double curve attaching face of the lift into contact with the shoe heel. This is due to the fact that it is mathematically impossible to develop a double curved surface into a plane surface. Such impossibility of development of a double curve surface of the lift into the plane of the slice heel when it is attached results in the formation of humps in the tread surface of the lift, due to the compressional stresses in all directionson the tread surface caused by flattening arches which exist in all radial planes normal to the double curved surface. This produces an uneven tread surface which causes uneven wear and gives the wearer the sensation of insecurity. Further, owing to the fact that all parts of the heel lift between the attaching nails are normally7 out of Contact with the shoe heel, the heel lift when walked upon will tend to move alternately toward and away from the shoe heel, placing a heavy strain upon the attaching nails which causes them to become loosened and often results in the lift coming entirely off of the shoe heel. Also, due to the flattening out of the tread surface under the weight of the wearerand the loosening of the nails, the heel lift under pressure will creep laterally upon the leather shoe heel and protrude or entend beyond the marginal edge of the latter, thus producing an unsightly. appearance.

Heels have been proposed and made embodying cylindrical surfaces in their attaching and tread faces, but in. all such cases it has been found impossible to make the entire faces of the lift truly cylindrical, with the result that certain portions of lifts of this type between the cylindrical surface and the margin of the lift are composed of double curved surfaces which are blended with the cylindrical surface, so as to show no line of demarkation. The necessity of such construction in heels of the cylindrical type is due to the fact that wit-hin practical limits of rubber heel construction it is impossible to produce a heel embodying an unbroken cylindrical surface and having an outline or periphery conforming to the average slice heel shape. It is obvious therefore that the development feature inherent in a cylindricalsurface is lost to a heel having but a part of its attaching and tread surfaces cylindrical.

The above noted serious disadvantages existing in the practical application and use of the double curve and so-called cylindrical heel lifts of the concave-convex type are entirely overcome by means of my present invention, and to this end I provide the heel lift with a completely developable attaching face comprising an unbroken conical surface.

It follows from the Vdefinition of a developable surface that a lift of this con-' tight hugging contact of the lift around its entire marginal edge and along the breast edge thereof, with the leather heel is produced. Thus I attain the essential object and purpose of the double curved type of heel lift with the complete elimination of its inherent disadvantages. l

It is a further object of my invention to provide a heel lift as above characterized which, when attached, will be of absolutely uniform thickness throughout its structure,

all parts of the developed attaching and tread surfaces of the lift lying in parallel planes and providing` an absolutely flat unbroken tread surface.

lilith the above and other objects in view the invention consists in the improved heel lift and in the several novel structural features thereof, as will be hereinafter more fully described, illustrated in the accompanying drawing` and subsequently incorporated in the subjoined claims. ,ln the drawing wherein l have illustrated one desirable and practical embodiment of the invention:

l. is a plan view illustrating a heel lift and showingdiagrammatically the manner in which the geometrical formation of the attaching` face of the lift is determined.

Fig. 2. is a vertical lona'itu'dinal sectional view through the lift.

Figure a vertical transverse sectional view taken on the line 9i-3 of Figure l, looking` toward the rear of the heel.

Figure 4l is sectional view on the line iQ-4l of Fig. l, looking in the direction of the arrows.

Figure 5 is a plan view illustrating in fall and brolren lines the comparative out line shapes of the heel lift before and after itis developed into a plane.

Figure (i illustrates the improved lift attached to a shoe heel and showing that the lift has a` perfectly fiat tread surface.

Referring in detail to the drawing and more particularly to Figure l thereof l have shown the resilient lift having` a curved outline or contour .l0 1ll2 corresponding to that of the average shape shoe heel, such as is common to the trade and which will hereinafter be referred to as the attaching fare edge. in the preferred embodiment illustrated this edge lies entirely in a plane. The breast edge of the lift is 'preferably a non-plane. curve which entends between the breast corners l0 and l?. of the lift. The central longitudinal section of the lift is a f 'ght line TLQO., placed at suitable angle with respeft to the plane of the attaching edge and the inclination of this line determines the 'depth of the breast' edge at its center point .9.0. which is the point of the attaching face most remote from the plane of the attaching' edge. rThe point l5 Ais in line with the central longitudinal section of the lift ile-F20 and constitutes a vertex; or converging point for the rectilinear elements of the 'desired surface.

rlhis line ll-l5 is used as a rectilinear generatrix of the attaching` face of the lift, by moving it so that it is in constant contact with the attaching face edge itl-1 l`i2 used as a directrix and always passes through the vertex The generation of this attaching surface may be more particularly described by considering that llfhl is the initial position of the generatrix and that it creates one-half of the surface by moving along the attaching face edge lO-ll and always convergent to the point l5 as shown by the broken lines such as 16-17 in Fig. l of the drawing. rihese lines represent typical positions of the generatrix during its progress from the point 1l to the point l() on the attaching face edge of the lift. is the surface is symmetrical with respect to the center line 11-20, the other half of the surface may be similarly generated by moving the generati-ix along the remaining portion of the attaching face edge between the points ll and l2. lt is obvious that the surface thus generated is conical in the general and broad sense of the term. rlhis surface is terminated by the breast line itl-l2 which corresponds to the line of the inter-section of the conical surface with a vertically disposed cylindrical surface touching the breast corners l0 and l2.

it will be apparent to one familiar with the methods of generating mathematically exact surfaces that there are other ways of expressing the geometrical construction of the improved heel lift. depending upon the assumed conditions. The foregoingl description therefore is in no sense intended as a limitation upon the scope of the present invention, being here given merely as a pre` ferred manner of clearly disclosing how the present invention may be produced.

As shown in Figure 3 of the drawing a transverse section through the lift taken in a plane perpendicular to the attaching face edge on the line 3 3 of Fig. l will be a smooth curve. It follows from the fact that the attaching` surface is conical that all other parallel transverse sections will be of similar form. This is indicated by the dotted lines 3-3 in Figures l and 3 of the drawings, said lines indicating` the curvature of the attaching face in a transverse sect-ion cut b v a perpendicular plane parallel to the section 3. These various transverse cur atnres of the attaching surface coutinuallv decrease in depth from the breast to the rear end li ot the lift.

Since conical surfaces of all varieties belongl to a class known as developahle surfaces or in other words, surfaces which may tlatten out or develop into a plane; it is obvious that the heel lift of my present invention has the inherent property of development so that the attaching surface is converted from a conical surface to a perfectly Hat; or plane surface when the lift is attached to the shoe heel by nails or other suitable attaching n'lcans such as are common in the trade. rThis feature gives to the presenti iinproved heel lift a distinct advantage over other types of heel lifts having double curved surfaces` which are not capable of development. lt will he seen that when my 'which represents a section in a vertical plane` taken on the line l--i of Figure l, it Will be observed that an arch of considerable depth exists between the rear end l1 of the attaching face edge and the breast corner 10. A'

lilre arch also exists in a similar vertical section extending from the point Il to the other breast corner l2. The effect incident to flattening' these two arches is to bring considerable pressure at the rear of the attaching face edge so that it lilrewise will be held in close hugging contact against the leather face of the heel. The central longitudinal section through the lift extending in a straight line Would not create pressure at the central point 20 along the breast edge against the heel face, but it Will be noted that all sections radiating from this point 20vto the attaching face edge of the lift are arches. The combined effect of breaking down these arches when the lift is flattened against the heel will result in producing the necessary pressure of the entire breast edge of the lift against the heel face to provide a satisfactory contact. In other words as any section extending from the breast edge to the attaching face edge except in planes intersecting the vertex l5 of the cone is an arch, the resultant effect of flattening out these arches produces pressure all along the breast line of the lift. It is thus apparent that the improved lift embodies a completely developable attaching surface Which will give the desired close hugging contact against the shoe heel face around the entire marginal edge of the lift.

In the foregoing description, I have referred mainly to the attaching face of the lift but it is apparent that the tread face thereof would, for the salte of having a heel of uniform thickness throughout in order to have a perfectly flat tread face when attached, correspond to a section of a parallel cone.

In addition to the advantages above pointed out, it will be evident to those familiar with the practical art, that the plungers of the moulds for the manufacture of my improved heel lift may be produced by a simple milling process, and therefore. do not require any special form of dies, such as are comnionly used in making moulds for lifts of the double curved concave-convex type, as heretofore produced in the art. The milling` process is more accurate than the die stamping process and therefore,I results in a more uniform and accurately constructed lift.

It is to be particularly noted that., while the einboiliment illustrated and described herein is a heel having its attaching face edge lying in a plane. the scope of my invention should not be limited to a lift so constructed, for a nonplane attaching face edge can readily be embodied in a heel of this type and as a matterof fact such an edge would likely result from assuming conditions other than those above assumed for the directrices of the conical surface. For oiainple, assuming that the curvature of the breast edge l? extending between the corners lll-l2 is first determined, the generatrii; may move along this breast edge from one breast corner to the other, always passing through the point l5 to produce a conical surface of indefinite area. The shape of a standart. shoe heel is then laidout on this conical surface extending from the breast corner l0 through the rearend l1 to the other breast corner l2 and the lift then cut from the material in accordance therewith. In this case, the attaching` face edge would not lie in a single plane, it being' understood of course that the curvature 4of the breast edge l? .is other than thatillustrated in the drawing In this suggested modification, only the opposite breast corners lil- 12 and the rear central point ll of the attaching face edge would lie in the same plane.

Havingthus described one practical and satisfactory embodiment of my invention it is nevertheless to be understood that the same is susceptible of many modifications, and I accordingly reserve the privilege of adopting all such changes as may be fairly embodied Within the spirit and scope of the invention claimed.

lhat I claim is:

l. A resilient heel lift of the concavo-convex type having a concave attaching face, every transverse cross-sectional element of which in planes perpendicular to the marginal edge of the lift is a continuous unbroken are, said arcs progressively increasing in radii from the breast edge to the rear end of the lift and all parts of said concave attaching face being completely developable into a plane surface.

A resilient heel lift of the concave-conver; type having an attaching face completely developable into a plane surface, said attaching face along its central longitudinal dimension extending in a straight line, and presenting arcs in all planes perpendicular to the longitudinal center line of the lift, sa id arcs being of gradually decreasing curvature from the breast edge to the rear end of the lift.

A resilient heel lift of the concavo-conver type having an attaching facecompletely developable into a plane surface, every rectinem element of seid attaching face extending` in e straight line between the breast' coge and the attaching face edge ot the l't colwergng to a con/nnen point 1oczlfed n spaced yelaton to the breast edge et the lift.

A resilient heel lift having zu attachall parts of which lie beton' e plane coinciding with the rear end of the attaching; ,lince edge and the breastcorners. seid :B ttechh ce cox'espondn in geometrica] n L u zx e section ox a conical surface.

5. xeslent heel litt hafng' an attachentng,v transverse fnculzzr arcs 'eseweljf decreasing depths from Vthe heflst edge to the real' end of the lift,

and Suid :frcs com-csp veiling in cnr Yatt-nre to the consecutive circumferential elements of the sinne conical sul''ace.

G. whent heel lft of' the concmo-con- Vex type having an ettachng face correponding in geometric-a1 form with a secon of n. conical surface and having a tread ance correspondieg in geometrical form with e section o conical surface, said lift hensc' ot ln'n't'olun thickness throughout its area angl seid attaching and trent]L snlfuces prec ting transverse arcs o' pfoglcssvely de- 'ensng depth from the breast edge to the under.

J @HRT TV. YEL/XR, J a. 

